you're mixing up ramsay and roose. roose was the one who stabbed robb at the red wedding and ramsay is the one torturing theon. he's roose's bastard, hence the name ramsay snow. so the letter was written, as signed by ramsay (roose's bastard)
He isnt mixing them up. He is saying (wondering) that the letter that Theons dad received was not from Roose but from Ramsey pretending to be Roose.

No she didn't. He told her if she needed him to give that coin to any man from Bravos and say Valhar Marghoulis...she just looked at the coin and said it. I took that to mean that she was remembering what he told her and plotting her next move, not that she summoned him. But I imagine she's gonna try to get the Hound to take her to Bravos. Hell, he might wanna join up too...might prefer being a faceless man to having a burned face.
